Now Italian prosecutors are going to have the chance to take a crack at Mr. Berlusconi. The country's highest court ruled Wednesday that a law he introduced that gave him immunity from criminal prosecution while in office is unconstitutional.

The ruling means that two trials in which Mr. Berlusconi is accused of serious corruption, and which were frozen when the immunity law was passed last summer, will now reopen.

So does this spell the beginning of the end for the 73-year-old prime minister?

Strangely enough, probably not, at least in the short term. His coalition partners continue to back him, and Italy's legal system moves at such a laborious pace that the cases could expire under the country's 10-year statute of limitations. Even if Berlusconi were to be convicted of a crime, he has recourse to two levels of appeal, a process that could take years to conclude.

Berlusconi's political life has been as charmed as his legal problems have been deep in recent years. Eight years ago, The Economist famously ran a cover story titled "Why Silvio Berlusconi is unfit to lead Italy." It chronicled legal investigations of the prime minister extending back to the early 1990s on allegations of "money-laundering, association with the Mafia, tax evasion, complicity in murder and bribery of politicians, judges and the finance ministry's police." Two months later, Italy made him prime minister, a post he held until 2006. Last April, he was returned to his post in a landslide.

On top of existing corruption allegations, in the past few months he has also been accused of sleeping with a prostitute at his mansion in Rome and of having an inappropriate relationship with an 18-year-old lingerie model.

In combative mood during an interview on Italian radio Wednesday night, he said: "The two trials against me are false, laughable, absurd, and I will show this to Italians by going on television, and I will defend myself in the courtroom and make my accusers look ridiculous and show everyone what stuff they are made of and what stuff I am made of."

Support still high

The billionaire media tycoon continues to enjoy high levels of support, despite the sex scandals and the fact that Italy is going through its worst recession since the Second World War.

His center-right People of Freedom bloc, which came to power 17 months ago, dominates both houses of parliament. And the personal approval ratings of the man who recently called himself "Superman" and a "bullfighter" continue to hover around 50 percent.

Meanwhile, his political opponents are in disarray. The main opposition Democratic Party has taken to infighting after its defeat last year and has failed to capitalize on Berlusconi's scandals, which have rocked the government since May, when Berlusconi's wife accused him of "consorting with underage girls" and demanded a divorce.

Nevertheless, the rejection of the immunity law has weakened him at a time when he was trying to repair his damaged reputation at home and abroad.

"This is a crucial moment for Berlusconi, very dramatic," says Renato Mannheimer, a political analyst at Milan University. "It is a very important decision, which will undoubtedly weaken Berlusconi politically, though not necessarily among ordinary people, because his approval ratings remain extremely high."

Having to appear at the reopened trials in Milan, where they were originally being held, will distract Berlusconi from the day-to-day job of governing the country, and worsen an already poisonous atmosphere between Italy's left and right.

As he fends off allegations of impropriety in his personal and business affairs, the prime minister is likely to shy away from the structural economic reforms that Italy desperately needs.

"Italy is in bad need of reforms to get the economy going and this makes those reforms even less likely, because Berlusconi will be less inclined or able to focus on any reform effort," says Tito Boeri, professor of economics at Milan's Bocconi University. "The ruling will make the government weaker and even less effective, but I don't think it will cause it to fall or affect its duration."